JP7747985B2 - Fluororubber crosslinking composition, molded article and sealing material - Google Patents

Description

This disclosure relates to a fluororubber cross-linking composition, a molded article, and a sealing material.

Patent Document 1 describes aromatic polyhydroxy compounds that can act as crosslinkers or co-curing agents for fluorinated elastomers as essential components in the final curable composition. One of the most useful aromatic polyphenols is the bisphenol compound hexafluoroisopropylidene-bis(4-hydroxybenzene), known as bisphenol AF.

Patent document 2 describes a composition containing a fluorocarbon elastomer gum, a fluoroaliphatic sulfonamide as a curing agent therefor, and a second curing agent selected from the group consisting of polyhydroxy compounds, polyamine compounds, and derivatives thereof.

Patent document 3 describes a composition containing a fluorocarbon elastomer gum and a vulcanizing agent for the same, characterized in that the vulcanizing agent is a composition containing one or a mixture of aromatic compounds having hydroxy and oxyallyl groups directly bonded to a carbon atom of an aromatic ring.

Patent Document 4 describes a composition for vulcanizing fluororubber, which contains (a) a fluorine-containing elastomer, (b) one or more substances selected from the group consisting of divalent metal oxides, divalent metal hydroxides, and mixtures of these metal oxides or metal hydroxides with metal salts of weak acids, (c) a polyhydroxy aromatic compound, and (d) a specific vulcanization accelerator.

Special Publication No. 64-418 Japanese Unexamined Patent Publication No. 60-215042 Japanese Unexamined Patent Publication No. 59-105046 Japanese Unexamined Patent Publication No. 63-268757

The objective of this disclosure is to provide a fluororubber cross-linking composition that contains a compound that does not contain fluorine atoms as a cross-linking agent and that can produce molded products that have excellent compression set properties at high temperatures, tensile strength, and heat resistance.

The present disclosure provides a composition for crosslinking fluororubber, which contains a polyol-crosslinkable fluororubber (a) and a crosslinking agent (b), wherein the crosslinking agent (b) is at least one selected from the group consisting of a compound represented by the following general formula (b) and a salt of said compound with an alkali metal, alkaline earth metal, or onium compound:

(In the formula, m and n independently represent an integer of 1 to 3. The hydrogen atoms bonded to the four benzene rings may be substituted with any substituent (excluding a hydroxy group, a sulfanyl group, an amino group, an acid group, a halogen atom, and a group containing a halogen atom).)

In the fluororubber cross-linking composition of the present disclosure, the fluororubber (a) preferably contains vinylidene fluoride units.
In the fluororubber cross-linking composition of the present disclosure, the content of the cross-linking agent (b) is preferably 0.5 to 50 mmol per 100 parts by mass of the fluororubber (a).
The fluororubber cross-linking composition of the present disclosure preferably further contains a cross-linking accelerator (c).
The fluororubber cross-linking composition of the present disclosure preferably further contains an acid acceptor (d).
The fluororubber cross-linking composition of the present disclosure preferably further contains 0.1 to 50 parts by mass of an acid acceptor (d) relative to 100 parts by mass of the fluororubber (a).
The fluororubber cross-linking composition of the present disclosure preferably further contains at least one acid acceptor (d) selected from the group consisting of metal oxides, metal hydroxides, alkali metal silicates, metal salts of weak acids, and hydrotalcites.

In the fluororubber cross-linking composition disclosed herein, it is preferable that the cross-linking agent (b) is at least one selected from the group consisting of compounds represented by the following formula (b1) and salts of the above compounds with alkali metals, alkaline earth metals, or onium compounds.

The present disclosure also provides a molded article or sealing material obtained from the above-mentioned fluororubber cross-linking composition.

According to the present disclosure, a fluororubber cross-linking composition can be provided that contains a compound that does not contain fluorine atoms as a cross-linking agent and can produce molded products that have excellent compression set properties at high temperatures, tensile strength, and heat resistance.

Specific embodiments of the present disclosure are described in detail below, but the present disclosure is not limited to the following embodiments.

The fluororubber cross-linking composition disclosed herein contains a polyol-cross-linkable fluororubber (a) and a cross-linking agent (b).

By using a crosslinkable composition containing bisphenol AF as a crosslinking agent, molded articles with excellent compression set properties at high temperatures can be obtained. However, because bisphenol AF is a fluorine-containing compound, if it adheres to equipment used for measuring or preparing the composition, cleaning the bisphenol AF from the equipment requires specialized incineration equipment to dispose of the residue, which can be costly. Therefore, there is a need for a polyol crosslinking agent that does not contain fluorine atoms and that can produce molded articles with excellent compression set properties at high temperatures.

The fluororubber cross-linking composition of the present disclosure contains a compound having the structure described below as a cross-linking agent. These compounds are easy to handle because they do not contain fluorine atoms. Furthermore, molded articles obtained from the fluororubber cross-linking composition of the present disclosure have excellent compression set properties and tensile strength at high temperatures, and also have excellent heat resistance, such as being resistant to changes in tensile strength even when the molded article is exposed to high temperatures.

The following describes each component of the disclosed fluororubber cross-linking composition.

(a) Polyol-crosslinkable fluororubber The polyol-crosslinkable fluororubber used in this disclosure is a fluororubber having a polyol-crosslinkable site. In this disclosure, the fluororubber is an amorphous fluoropolymer. "Amorphous" means that the magnitude of the melting peak (ΔH) appearing in differential scanning calorimetry (DSC) (heating rate 20°C/min) or differential thermal analysis (DTA) (heating rate 20°C/min) of the fluoropolymer is 4.5 J/g or less. Fluororubber exhibits elastomeric properties by crosslinking. Elastomeric properties mean the property that a polymer can be stretched and retains its original length when the force required to stretch the polymer is no longer applied.

Examples of the polyol-crosslinkable moiety include a moiety having a vinylidene fluoride (VdF) unit. Among them, fluororubbers containing VdF units are preferred because the effect of using the crosslinking agent (b) is easily exhibited. Examples of fluororubbers having a polyol-crosslinkable moiety include:
a vinylidene fluoride (VDF) fluoroelastomer having substantially no polar terminal group, as described in JP-A-2003-277563;
a vinylidene fluoride-based fluoroelastomer comprising a repeating unit derived from vinylidene fluoride (VDF) and a repeating unit derived from at least one additional (per)fluorinated monomer, as described in JP-A-2018-527449;
The cured fluoroelastomer may be, for example, 100 parts (phr) of a cured fluoroelastomer having a small amount of fluorine of less than 67% by weight as described in JP-A-7-316377, which contains 40 to 68% by weight of vinylidene fluoride (VDF) units and 20 to 50% by weight of hexafluoropropylene (HFP) units in a total amount of 100, and optionally contains one or more comonomers having ethylene unsaturation.

Examples of fluororubbers having a polyol crosslinkable site include non-perfluoro fluororubbers and fluororubbers containing —CH ₂ — (methylene group) in the main chain.

Examples of fluororubbers having polyol-crosslinkable moieties include VdF-based fluororubbers and rubbers having polyol-crosslinkable functional moieties such as double bonds in the side chains and/or main chains. Examples of VdF-based fluororubbers include tetrafluoroethylene (TFE)/propylene/VdF-based fluororubbers, ethylene/hexafluoropropylene (HFP)/VdF-based fluororubbers, VdF/HFP-based fluororubbers, and VdF/TFE/HFP-based fluororubbers. These fluororubbers having polyol-crosslinkable moieties can be used alone or in any combination within the scope that does not impair the effects of the present disclosure.

As VdF-based fluororubbers, those represented by the following general formula (1) are preferred.

-(M ¹ )-(M ² )-(N ¹ )- (1)
(In the formula, the structural unit ^M1 is a structural unit derived from vinylidene fluoride ( ^m1 ), the structural unit ^M2 is a structural unit derived from a fluorine-containing ethylenic monomer ( ^m2 ), and the structural unit ^N1 is a repeating unit derived from the monomer ( ^m1 ) and a monomer ( ⁿ¹ ) copolymerizable with the monomer ( ^m2 ).)

Among the VdF-based fluororubbers represented by general formula (1), those containing 30 to 85 mol% of structural units ^M1 and 55 to 15 mol% of structural units ^M2 are preferred, and more preferably 50 to 80 mol% of structural units ^M1 and 50 to 20 mol% of structural units ^M2 . The amount of structural units ^N1 is preferably 0 to 20 mol% based on the total amount of structural units ^M1 and ^M2 .

As the fluorine-containing ethylenic monomer (m ² ), one or more monomers can be used, and examples thereof include TFE, chlorotrifluoroethylene (CTFE), trifluoroethylene, HFP, trifluoropropylene, tetrafluoropropylene, pentafluoropropylene, trifluorobutene, tetrafluoroisobutene, perfluoro(alkyl vinyl ether) (PAVE), and fluorine-containing ethylenic monomers represented by the general formula (2):
CF ₂ =CFO(Rf ¹ O) _q (Rf ² O) _r Rf ³ (2)
(wherein ^Rf1 and ^Rf2 each independently represent a linear or branched perfluoroalkylene group having 1 to 6 carbon atoms, ^{Rf3 each} independently represent a linear or branched perfluoroalkyl group having 1 to 6 carbon atoms, and q and r each independently represent an integer of 0 to 6 (with the proviso that 0<q+r≦6)), a fluorine-containing monomer represented by general formula (3):
CHX ¹¹ =CX ¹² Rf ⁴ (3)
(wherein one of ^X11 and ^X12 is H and the other is F, and ^Rf4 is a linear or branched fluoroalkyl group having 1 to 12 carbon atoms), and fluorine-containing monomers such as vinyl fluoride, among which TFE, HFP and PAVE are preferred.

The monomer (n ¹ ) may be any monomer that is copolymerizable with the monomer (m ¹ ) and the monomer (m ² ), and examples thereof include ethylene, propylene, alkyl vinyl ether, a monomer that provides a crosslinking site, a bisolefin compound, etc. These may be used alone or in any combination.

Examples of the monomer that provides such a crosslinking site include those represented by the general formula (4):
CY ¹ ₂ = CY ¹ - Rf ⁵ CHR ¹ X ¹ (4)
(wherein Y ¹ is independently a hydrogen atom, a fluorine atom, or —CH ₃ ; Rf ⁵ is a fluoroalkylene group, a perfluoroalkylene group, a fluoropolyoxyalkylene group, or a perfluoropolyoxyalkylene group; R ¹ is a hydrogen atom or —CH ₃ ; and X ¹ is an iodine atom or a bromine atom), an iodine- or bromine-containing monomer represented by general formula (5):
CF ₂ =CFO(CF ₂ CF(CF ₃ )O) _m (CF ₂ ) _n −X ² (5)
(wherein m is an integer of 0 to 5, n is an integer of 1 to 3, and ^X2 is a cyano group, a carboxyl group, an alkoxycarbonyl group, a bromine atom, or an iodine atom), a monomer represented by general formula (6):
_CH2 =CH( _CF2 ) _pI (6)
(wherein p is an integer of 1 to 10), and examples thereof include iodine-containing monomers such as perfluoro(6,6-dihydro-6-iodo-3-oxa-1-hexene) and perfluoro(5-iodo-3-oxa-1-pentene) as described in Japanese Patent Publication No. 5-63482 and Japanese Patent Laid-Open Publication No. 7-316234, and CF ₂ ═CFOCF ₂ CF ₂ CH ₂ as described in Japanese Patent Laid-Open Publication No. 4-217936. I, iodine-containing monomers such as 4-iodo-3,3,4,4-tetrafluoro-1-butene described in JP-A-61-55138, bromine-containing monomers described in JP-A-4-505341, cyano group-containing monomers, carboxyl group-containing monomers, and alkoxycarbonyl group-containing monomers described in JP-A-4-505345 and JP-A-5-500070, etc. These can be used alone or in any combination.
As the bisolefin compound, those described in JP-A-8-12726 can be used.

Specific examples of the VdF-based fluororubbers include VdF/HFP-based rubbers, VdF/HFP/TFE-based rubbers, VdF/TFE/PAVE-based fluororubbers, VdF/CTFE-based rubbers, and VdF/CTFE/TFE-based rubbers.

Among these, the polyol-crosslinkable fluororubber is preferably a fluororubber composed of VdF and at least one other fluorine-containing monomer, and is particularly preferably at least one rubber selected from the group consisting of VdF/HFP-based fluororubber, VdF/TFE/HFP-based fluororubber, and VdF/TFE/PAVE-based fluororubber, and more preferably at least one rubber selected from the group consisting of VdF/HFP-based fluororubber and VdF/TFE/HFP-based fluororubber.

The fluororubber preferably has a Mooney viscosity at 121°C (ML1+10(121°C)) of 1 or more, more preferably 3 or more, even more preferably 5 or more, and particularly preferably 10 or more. It is also preferably 200 or less, more preferably 170 or less, even more preferably 150 or less, even more preferably 130 or less, and particularly preferably 100 or less. Mooney viscosity is measured in accordance with ASTM D1646-15 and JIS K6300-1:2013.

The fluorine content of the fluororubber is preferably 50 to 75% by mass. It is more preferably 60 to 73% by mass, and even more preferably 63 to 72% by mass. The fluorine content can be calculated from the composition ratio of the monomer units that make up the fluororubber.

The fluororubber preferably has a glass transition temperature of -50 to 0°C. The glass transition temperature can be determined by obtaining a DSC curve using a differential scanning calorimeter by heating 10 mg of a sample at a rate of 20°C/min, and finding the temperature at the intersection of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve.

The fluororubber described above can be manufactured by conventional methods.

(b) Crosslinking Agent The fluororubber crosslinking composition of the present disclosure contains a crosslinking agent, which is at least one selected from the group consisting of compounds represented by the following general formula (b) and salts of the above compounds with alkali metals, alkaline earth metals, or onium compounds:

(In the formula, m and n independently represent an integer of 1 to 3. The hydrogen atoms bonded to the four benzene rings may be substituted with any substituent (excluding a hydroxy group, a sulfanyl group, an amino group, an acid group, a halogen atom, and a group containing a halogen atom).)

The compound represented by general formula (b) contains a fluorene ring, and at least one hydroxy group is bonded to each of the two benzene rings bonded to the 9-position of the fluorene ring. The number of hydroxy groups bonded to the two benzene rings can be selected from 2 to 6, and the bonding positions of the hydroxy groups are not limited. m and n represent the number of hydroxy groups bonded to each of the two benzene rings bonded to the 9-position of the fluorene ring. m and n may, for example, independently be 1 or 2. In this case, for example, two hydroxy groups may be bonded to each of the para positions of the two benzene rings, or four hydroxy groups may be bonded to each of the meta and para positions of the two benzene rings. Preferably, m and n are integers between 1 and 2, and more preferably 1. Furthermore, having a hydroxy group at the para position of the benzene ring is preferred in terms of crosslinking properties and favorable tensile strength and compression set properties of molded articles.

Of the hydrogen atoms bonded to the fluorene ring and the two benzene rings, those not substituted with hydroxy groups may be substituted with substituents other than hydroxy groups, sulfanyl groups, amino groups, acid groups, halogen atoms, and groups containing halogen atoms, or may be unsubstituted. Examples of substituents include cyano groups and alkyl groups having 1 to 10 carbon atoms. The substituents are those that do not contain halogen atoms, such as fluorine atoms and groups containing fluorine atoms. Therefore, the compound represented by general formula (b) does not contain fluorine atoms.

An acid group is a group that has a hydrogen atom that can be ionized as a proton. In this disclosure, acid groups also include acid bases in which this hydrogen atom has been replaced with another atom (such as an alkali metal atom). Examples of acid groups include oxo acid groups (groups that have an atom bonded to a hydroxy group (-OH) and an oxo group (=O), and in which the hydroxy group can release a proton). Typical examples of acid groups include carboxy groups, sulfo groups, sulfino groups, phosphate groups, phosphonate groups, and the acid bases of these groups.

The crosslinking agent may be a salt of a compound represented by general formula (b) with an alkali metal, a salt of a compound represented by general formula (b) with an alkaline earth metal, or a salt of a compound represented by general formula (b) with an onium compound. Among these salts, a salt of a compound represented by general formula (b) with an onium compound is preferred. The salt of the above compound with an onium compound is an onium salt composed of an anion portion derived from the above compound and a cation portion derived from the onium compound. By using an onium salt as crosslinking agent (b), the onium salt not only acts as a crosslinking agent but also as a crosslinking accelerator.

The compound represented by general formula (b), the salt of the compound represented by general formula (b) with an alkali metal, the salt of the compound represented by general formula (b) with an alkaline earth metal, or the salt of the compound represented by general formula (b) with an onium compound can be used alone or in combination.

A salt of a compound represented by general formula (b) with an onium compound can be obtained by reacting a compound represented by general formula (b) with an alkaline substance such as sodium hydroxide in water or an organic solvent, or with metallic sodium in an organic solvent, followed by further reaction with an onium compound such as benzyltriphenylphosphonium chloride, and then distilling off the water or organic solvent. If necessary, the reaction product solution can be filtered or the reaction product can be washed with water or an organic solvent to remove by-products such as sodium chloride.

As an alkali metal, Na or K is preferred. As an alkaline earth metal, Ca or Mg is preferred.

Examples of onium salts include ammonium salts, phosphonium salts, and sulfonium salts.

Onium compounds that constitute onium salts include ammonium compounds, phosphonium compounds, and sulfonium compounds. In this disclosure, onium compounds do not contain fluorine atoms.

As the onium compound constituting the onium salt, ammonium compounds and phosphonium compounds are preferred, phosphonium compounds are more preferred, and quaternary phosphonium compounds are even more preferred, with benzyltriphenylphosphonium being particularly preferred. As the ammonium compound, quaternary ammonium compounds are preferred, with 8-benzyl-1,8-diazabicyclo[5,4,0]-7-undecenium and benzyldimethyloctadecylammonium being more preferred.

The crosslinking agent is preferably at least one selected from the group consisting of compounds represented by the following formula (b1) and salts of the above compounds with alkali metals, alkaline earth metals, or onium compounds.

The crosslinking agent can be mixed with other compounds. Examples of mixtures containing a crosslinking agent include a solid solution of the crosslinking agent and a crosslinking accelerator, and a mixture of the crosslinking agent and a compound capable of dissolving it. As a mixture of a crosslinking agent and a crosslinking accelerator, a mixture of a compound represented by general formula (b) and a quaternary phosphonium salt or a mixture of a compound represented by general formula (b) and a quaternary ammonium salt is preferred, a mixture of a compound represented by general formula (b) and a quaternary phosphonium salt is more preferred, and a mixture of a compound represented by general formula (b) and benzyltriphenylphosphonium chloride is even more preferred.

The content of the crosslinking agent is preferably 0.5 to 50 mmol, more preferably 1.0 mmol or more, even more preferably 2.0 mmol or more, more preferably 40 mmol or less, even more preferably 30 mmol or less, and particularly preferably 20 mmol or less, per 100 parts by mass of polyol-crosslinkable fluororubber, as this allows for the production of molded products with even better tensile strength and high-temperature compression set properties.

(c) Crosslinking Accelerator The fluororubber crosslinking composition of the present disclosure may further contain a crosslinking accelerator. The use of a crosslinking accelerator can accelerate the crosslinking reaction by accelerating the formation of intramolecular double bonds in the dehydrofluorination reaction of the fluororubber main chain. When a compound represented by general formula (b) is used as the crosslinking agent, it is preferable to use a crosslinking accelerator together with the crosslinking agent. Even when an onium salt is used as the crosslinking agent, a crosslinking accelerator can be used together with the crosslinking agent, but it is not necessarily required. The amount of crosslinking accelerator can be adjusted appropriately depending on the crosslinking conditions and the physical properties of the molded product. Increasing the amount of crosslinking accelerator speeds up the crosslinking reaction or enables crosslinking at a lower temperature, but tends to worsen the compression set properties. Conversely, reducing the amount of crosslinking accelerator slows down the crosslinking reaction, but tends to improve the compression set properties.

Onium salts (excluding salts of a compound represented by general formula (b) and an onium compound) are generally used as crosslinking accelerators for polyol crosslinking systems. The onium salt is not particularly limited, and examples include ammonium salts such as quaternary ammonium salts, phosphonium salts such as quaternary phosphonium salts, and sulfonium salts. Of these, quaternary ammonium salts and quaternary phosphonium salts are preferred.

Quaternary ammonium salts are not particularly limited, and examples include 8-methyl-1,8-diazabicyclo[5,4,0]-7-undecenium chloride, 8-methyl-1,8-diazabicyclo[5,4,0]-7-undecenium iodide, 8-methyl-1,8-diazabicyclo[5,4,0]-7-undecenium hydroxide, and 8-methyl-1,8-diazabicyclo[5,4,0]-7-undecenium methylsulfate. , 8-ethyl-1,8-diazabicyclo[5,4,0]-7-undecenium bromide, 8-propyl-1,8-diazabicyclo[5,4,0]-7-undecenium bromide, 8-dodecyl-1,8-diazabicyclo[5,4,0]-7-undecenium chloride, 8-dodecyl-1,8-diazabicyclo[5,4,0]-7-undecenium hydroxide, 8-eicosyl-1,8-diazabicyclo[5,4,0]-7 -undecenium chloride, 8-tetracosyl-1,8-diazabicyclo[5,4,0]-7-undecenium chloride, 8-benzyl-1,8-diazabicyclo[5,4,0]-7-undecenium chloride (hereinafter referred to as DBU-B), 8-benzyl-1,8-diazabicyclo[5,4,0]-7-undecenium hydroxide, 8-phenethyl-1,8-diazabicyclo[5,4,0]-7-undecenium chloride, 8-(3-phenylpropyl)-1,8-diazabicyclo[5,4,0]-7-undecenium chloride, benzyldimethyloctadecylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium chloride, benzyltributylammonium chloride, benzyltriethylammonium chloride, tetrabutylammonium hydrogen sulfate, tetrabutylammonium hydroxide, and the like. Among these, DBU-B or benzyldimethyloctadecylammonium chloride is preferred from the viewpoint of crosslinkability and physical properties of the crosslinked product.

Furthermore, the quaternary phosphonium salt is not particularly limited, and examples include tetrabutylphosphonium chloride, benzyltriphenylphosphonium chloride (hereinafter referred to as BTPPC), benzyltrimethylphosphonium chloride, benzyltributylphosphonium chloride, tributylallylphosphonium chloride, tributyl-2-methoxypropylphosphonium chloride, and benzylphenyl(dimethylamino)phosphonium chloride. Of these, benzyltriphenylphosphonium chloride (BTPPC) is preferred in terms of crosslinkability and the physical properties of the crosslinked product.

The content of the crosslinking accelerator is preferably 0.1 to 10 parts by mass, more preferably 0.1 to 5 parts by mass, even more preferably 0.1 to 3 parts by mass, and particularly preferably 0.1 to 2 parts by mass, per 100 parts by mass of the polyol-crosslinkable fluororubber, because this allows for an appropriate crosslinking reaction rate and the production of even better molded products due to the compression set properties at high temperatures. Note that when the crosslinking agent is a salt of a compound represented by general formula (b) and an onium compound, the content of the crosslinking accelerator includes the mass of the cation portion of the crosslinking agent (i.e., the cation derived from the onium compound).

(d) Acid Acceptor The fluororubber cross-linking composition of the present disclosure may further contain an acid acceptor. By containing an acid acceptor, the cross-linking reaction of the fluororubber cross-linking composition proceeds more smoothly, and the tensile strength and the compression set properties at high temperatures are further improved.

Examples of acid acceptors include metal oxides such as magnesium oxide, calcium oxide, and bismuth oxide; metal hydroxides such as calcium hydroxide; alkali metal silicates such as hydrotalcite and sodium metasilicate, which are described in JP-T-2011-522921; and metal salts of weak acids such as those described in JP-A-2003-277563. Examples of metal salts of weak acids include carbonates, benzoates, oxalates, and phosphites of Ca, Sr, Ba, Na, and K.

As the acid acceptor, at least one selected from the group consisting of metal oxides, metal hydroxides, alkali metal silicates, metal salts of weak acids, and hydrotalcite is preferred, as this allows for the production of molded articles with even better compression set properties at high temperatures. Hydrated sodium metasilicate, calcium hydroxide, magnesium oxide, bismuth oxide, and hydrotalcite are more preferred. Furthermore, if the resulting molded article requires good water resistance, acid resistance, or resistance to organic acid esters, including biodiesel, at least one selected from the group consisting of bismuth oxide and hydrotalcite is preferred.

In the fluororubber cross-linking composition, the content of the acid acceptor is preferably 0.1 to 100 parts by mass, more preferably 1 to 50 parts by mass, even more preferably 1 to 30 parts by mass, and particularly preferably 1 to 20 parts by mass per 100 parts by mass of polyol-cross-linkable fluororubber, as this allows for the production of molded products with even better tensile strength and compression set properties at high temperatures.

Increasing the acid acceptor content tends to decrease the water resistance, acid resistance, and resistance to organic acid esters, including biodiesel, of the resulting molded article. Conversely, decreasing the acid acceptor content tends to decrease the crosslinking rate and mechanical properties due to a decrease in crosslink density. Therefore, the acid acceptor content can be selected depending on the intended use of the resulting molded article. Furthermore, when an acid acceptor other than calcium hydroxide is contained, reducing the calcium hydroxide content to 0 to 1.5 parts by mass, for example, and then adjusting the content of the other acid acceptor to adjust the crosslink density can result in a molded article with even better compression set properties at high temperatures.

(e) Other Components The fluororubber cross-linking composition may optionally contain various additives that are commonly used in fluororubber cross-linking compositions, such as fillers (carbon black, bituminous coal, barium sulfate, diatomaceous earth, calcined clay, talc, wollastonite, carbon nanotubes, etc.), processing aids, colorants, stabilizers, tackifiers (coumarone resin, coumarone-indene resin, etc.), electrical conductivity imparting agents, thermal conductivity imparting agents, surface non-tackifying agents, flexibility imparting agents, heat resistance improvers, flame retardants, foaming agents, and antioxidants described in WO 2012/023485. One or more commonly used cross-linking agents and cross-linking accelerators different from those described above may also be incorporated. Of these, preferred carbon blacks are thermal carbon black and furnace carbon black, with MT carbon black, FT carbon black, and SRF carbon black being more preferred. When carbon black or carbon black with a relatively large particle size, such as FT carbon black, is blended, molded products with excellent compression set properties are obtained, while when carbon black with a fine particle size is blended, molded products with excellent strength and elongation are obtained. By blending different grades together, it is possible to achieve a balance of these properties.

The processing aids include plasticizers and release agents, and are not particularly limited. Examples include synthetic fatty acid esters, waxes containing natural fatty acid esters, fatty amines such as stearylamine, fatty acid amides such as stearic acid amide, fatty alcohols, synthetic waxes such as polyethylene wax, phosphate esters such as tricresyl phosphate, and silicone-based processing aids. Blending two or more types in appropriate amounts as needed can improve the balance between mold releasability during molding and the physical properties of the molded product. The processing aids may be blended within a range that does not impair the effects of the present disclosure.

The content of fillers such as carbon black is not particularly limited, but is preferably 0 to 300 parts by mass, more preferably 1 to 150 parts by mass, even more preferably 2 to 100 parts by mass, and particularly preferably 2 to 75 parts by mass, per 100 parts by mass of polyol-crosslinkable fluororubber.

The content of processing aids such as wax is preferably 0 to 10 parts by mass, and more preferably 0 to 5 parts by mass, per 100 parts by mass of polyol-crosslinkable fluororubber. The use of processing aids, plasticizers, and release agents tends to reduce the mechanical properties and sealing ability of the resulting molded product, so it is necessary to adjust the content of these agents within a range that allows for the desired properties of the resulting molded product.

The fluororubber cross-linking composition may contain a dialkyl sulfone compound. The inclusion of a dialkyl sulfone compound increases the cross-linking efficiency of the fluororubber cross-linking composition, accelerates the cross-linking rate, further improves compression set properties, and improves the fluidity of the rubber material. Examples of dialkyl sulfone compounds include dimethyl sulfone, diethyl sulfone, dibutyl sulfone, methyl ethyl sulfone, diphenyl sulfone, and sulfolane. Among these, sulfolane is preferred from the standpoints of cross-linking efficiency and compression set properties, as well as its suitable boiling point. The content of the dialkyl sulfone compound is preferably 0 to 10 parts by mass, more preferably 0 to 5 parts by mass, and particularly preferably 0 to 3 parts by mass, per 100 parts by mass of the fluororubber. When the fluororubber cross-linking composition of the present disclosure contains a dialkyl sulfone compound, the lower limit of the dialkyl sulfone compound content may be, for example, 0.1 parts by mass or more per 100 parts by mass of the fluororubber.

The above dialkyl sulfone compound and the above processing aid may be blended together, as this will result in a good balance of crosslinking speed, fluidity of the rubber material during molding, mold release properties during molding, and mechanical properties of the molded product.

The fluororubber cross-linking composition can be obtained by kneading the fluororubber (a), cross-linking agent (b), cross-linking accelerator (c), acid acceptor (d), and other components (e) using a commonly used rubber kneading device. Examples of rubber kneading devices that can be used include rolls, kneaders, Banbury mixers, internal mixers, and twin-screw extruders.

In addition, in order to uniformly disperse each component in the rubber, a method may be used in which the fluororubber (a), cross-linking agent (b), and cross-linking accelerator (c) are melted and kneaded at a high temperature of 100 to 200°C using an enclosed kneading device such as a kneader, and then the acid acceptor (d), other components (e), etc. are kneaded at a relatively low temperature below this temperature.

Furthermore, dispersibility can be further improved by mixing the fluororubber (a), crosslinking agent (b), crosslinking accelerator (c), acid acceptor (d), and other components (e), leaving the mixture at room temperature for 12 hours or more, and then mixing it again.

<Molded product>
The molded article of the present disclosure can be obtained by crosslinking the fluororubber crosslinking composition. Alternatively, the molded article of the present disclosure can be obtained by molding and crosslinking the fluororubber crosslinking composition. The fluororubber crosslinking composition can be molded by a conventionally known method. The molding and crosslinking methods and conditions may be within the range of known methods and conditions for the molding and crosslinking employed. The order of molding and crosslinking is not limited, and molding may be followed by crosslinking, crosslinking may be followed by molding, or molding and crosslinking may be performed simultaneously.

Examples of molding methods include, but are not limited to, compression molding, casting, injection molding, extrusion molding, and rotocure molding. Crosslinking methods include steam crosslinking, heat crosslinking, and radiation crosslinking, with steam crosslinking and heat crosslinking being preferred. Specific crosslinking conditions, which are not limited to, are typically a temperature range of 140-250°C, a crosslinking time of 1 minute to 24 hours, and can be determined appropriately depending on the types of crosslinking agent (b), crosslinking accelerator (c), and acid acceptor (d).

In addition, by heating the resulting molded article in an oven or the like, it is possible to improve mechanical properties such as tensile strength, heat resistance, and high-temperature compression set properties. Specific crosslinking conditions, which are not limited to these, are typically in the temperature range of 140 to 300°C and the time range of 30 minutes to 72 hours, and can be determined appropriately depending on the types of crosslinking agent (b), crosslinking accelerator (c), acid acceptor (d), etc.

The molded article of the present disclosure has excellent properties such as heat resistance, oil resistance, chemical resistance, and flexibility, and further has excellent compression set properties at high temperatures. Therefore, the molded article of the present disclosure is generally used in areas that come into contact with other materials and slide, seal or seal other materials or substances, or are used for vibration and sound insulation, and can be used as various parts in various fields such as the automotive, aircraft, and semiconductor industries. In particular, the molded article of the present disclosure has excellent compression set properties at high temperatures, making it suitable for use as a sealing material.

Fields in which they are used include, for example, semiconductor-related fields, automobiles, aircraft, space and rockets, ships, chemicals such as chemical plants, pharmaceuticals such as medicines, photography such as developing machines, printing such as printing machines, painting such as painting equipment, analytical and physicochemical machinery such as analytical instruments and meters, food equipment including food plant equipment and household goods, food beverage manufacturing equipment, pharmaceutical manufacturing equipment, medical parts, chemical transport equipment, nuclear plant equipment, steel such as steel plate processing equipment, general industry, electricity, fuel cells, electronic parts, optical equipment parts, space equipment parts, petrochemical plant equipment, energy resource exploration and mining equipment parts for oil and gas, oil refining, and oil transportation equipment parts.

Examples of uses for molded products include various sealing materials and packings such as rings, packings, gaskets, diaphragms, oil seals, bearing seals, lip seals, plunger seals, door seals, lip and face seals, gas delivery plate seals, wafer support seals, and barrel seals. As sealing materials, they can be used in applications requiring heat resistance, solvent resistance, chemical resistance, and non-stick properties.

It can also be used for tubes, hoses, rolls, various rubber rolls, flexible joints, rubber plates, coatings, belts, dampers, valves, valve seats, valve bodies, chemical-resistant coating materials, laminating materials, lining materials, etc.

The cross-sectional shapes of the above rings, gaskets, and seals may be of various shapes, such as square, O-shaped, or ferrule-shaped, or may be irregular shapes such as D-shaped, L-shaped, T-shaped, V-shaped, X-shaped, or Y-shaped.

In the above-mentioned semiconductor-related fields, the present invention can be used, for example, in semiconductor manufacturing equipment, liquid crystal panel manufacturing equipment, plasma panel manufacturing equipment, plasma display panel manufacturing equipment, plasma addressed liquid crystal panel manufacturing equipment, organic EL panel manufacturing equipment, field emission display panel manufacturing equipment, solar cell substrate manufacturing equipment, semiconductor conveying equipment, etc. Examples of such equipment include CVD equipment, gas control equipment such as semiconductor gas control equipment, dry etching equipment, wet etching equipment, plasma etching equipment, reactive ion etching equipment, reactive ion beam etching equipment, sputter etching equipment, ion beam etching equipment, oxidation diffusion equipment, sputtering equipment, ashing equipment, plasma ashing equipment, cleaning equipment, ion implantation equipment, plasma CVD equipment, exhaust equipment, exposure equipment, polishing equipment, film formation equipment, dry etching cleaning equipment, UV/ _O3 cleaning equipment, ion beam cleaning equipment, laser beam cleaning equipment, plasma cleaning equipment, gas etching cleaning equipment, extraction cleaning equipment, Soxhlet extraction cleaning equipment, high temperature and high pressure extraction cleaning equipment, microwave extraction cleaning equipment, supercritical extraction cleaning equipment, cleaning equipment using hydrofluoric acid, hydrochloric acid, sulfuric acid, ozone water, etc., steppers, coater developers, CMP equipment, excimer laser exposure equipment, chemical liquid piping, gas piping, _NF3 plasma treatment, O Examples of such equipment include equipment for performing plasma treatment such as plasma treatment ₍₂₎ and fluorine plasma treatment, heat treatment film formation equipment, wafer transport equipment, wafer cleaning equipment, silicon wafer cleaning equipment, silicon wafer processing equipment, equipment used in LP-CVD processes, equipment used in lamp annealing processes, and equipment used in reflow processes.

Specific uses in the semiconductor-related field include, for example, various sealing materials such as O-rings and gaskets for gate valves, quartz windows, chambers, chamber lits, gates, bell jars, couplings, and pumps; various sealing materials such as O-rings for resist developer and stripper solutions, hoses and tubes; linings and coatings for resist developer tanks, stripper tanks, wafer cleaning solution tanks, and wet etching tanks; pump diaphragms; rolls for transporting wafers; hose tubes for wafer cleaning solutions; sealing materials for clean equipment such as sealants for clean rooms; sealing materials for storage cabinets that store semiconductor manufacturing equipment and devices such as wafers; and diaphragms for transporting chemical solutions used in the semiconductor manufacturing process.

In the automotive field, the material can be used in the engine itself, main drive systems, valve trains, lubrication and cooling systems, fuel systems, intake and exhaust systems, drivetrain transmission systems, chassis steering systems, brake systems, as well as electrical components such as basic electrical components, control system electrical components, and equipment electrical components. The automotive field also includes motorcycles.

In the engine body and its peripheral devices as described above, molded products can be used for various sealing materials that require heat resistance, oil resistance, fuel oil resistance, engine cooling antifreeze resistance, and steam resistance. Examples of such sealing materials include gaskets, shaft seals, valve stem seals, etc.; non-contact or contact type packings such as self-sealing packings, piston rings, split ring type packings, mechanical seals, and oil seals; bellows, diaphragms, hoses, tubes; as well as electrical wires, cushioning materials, vibration-damping materials, and various sealing materials used in belt AT devices.

Specific uses in the above fuel systems include fuel injectors, cold start injectors, fuel line quick connectors, sender flange quick connectors, fuel pumps, fuel tank quick connectors, gasoline mixing pumps, gasoline pumps, fuel tube bodies, fuel tube connectors, O-rings used in injectors, etc.; exhaust system manifolds, fuel filters, pressure regulating valves, canisters, fuel tank caps, fuel pumps, fuel tanks, fuel tank sender units, fuel injection devices, high-pressure fuel pumps, fuel line connector systems, pump timing control valves, suction connectors, etc. Seals used in control valves, solenoid sub-assemblies, fuel cut valves, etc.; canister purge solenoid valve seals, on-board refueling vapor recovery (ORVR) valve seals, fuel pump oil seals, fuel sender seals, fuel tank rollover valve seals, filler seals, injector seals, filler cap seals, filler cap valve seals; fuel hoses, fuel supply hoses, fuel return hoses, vapor (evaporative) hoses, vent (breather) hoses, filler hoses, filler neck hoses, hoses inside fuel tanks (in-tank hoses), carburetor connectors Hoses such as control hoses, fuel inlet hoses, and fuel breather hoses; gaskets used in fuel filters and fuel line connector systems, and flange gaskets used in carburetors; line materials such as vapor recovery lines, fuel feed lines, and vapor/ORVR lines; diaphragms used in canisters, ORVRs, fuel pumps, fuel tank pressure sensors, gasoline pumps, carburetor sensors, composite air control devices (CACs), pulsation dampers, canisters, autococks, and pressure regulator diaphragms for fuel injection systems; fuel pump valves, carburetor needle valves rollover check valves, check valves; vents (breathers), tubes used inside fuel tanks; tank gaskets for fuel tanks, etc., gaskets for carburetor accelerator pump pistons; fuel sender vibration isolation parts for fuel tanks; O-rings and diaphragms for controlling fuel pressure; accelerator pump cups; in-tank fuel pump mounts; injector cushion rings for fuel injection devices; injector seal rings; carburetor needle valve core valves; carburetor accelerator pump pistons; valve seats for composite air control systems (CAC); fuel tank bodies; and sealing parts for solenoid valves.

Specific uses in the above brake systems include diaphragms used in master bags, hydraulic brake hoses, air brakes, and air brake brake chambers; hoses used in brake hoses, brake oil hoses, vacuum brake hoses, etc.; various sealing materials such as oil seals, O-rings, gaskets, and brake piston seals; atmospheric valves and vacuum valves for master bags, and check valves for brake valves; piston cups (rubber cups) and brake cups for master cylinders; boots for hydraulic brake master cylinders and vacuum boosters, and wheel cylinders of hydraulic brakes, and O-rings and grommets for anti-lock braking systems (ABS).

Specific uses of the above basic electrical components include insulators and sheaths for electrical wires (harnesses), tubes for harness exterior parts, and grommets for connectors.

Specific uses in control system electrical components include coating materials for various sensor wires.

Specific uses for the above-mentioned electrical equipment parts include O-rings and packing for car air conditioners, cooler hoses, high-pressure air conditioning hoses, air conditioning hoses, gaskets for electronic throttle units, plug boots for direct ignition, and distributor diaphragms. It can also be used to bond electrical parts.

Specific uses in the above intake and exhaust systems include gaskets used in intake manifolds, exhaust manifolds, etc., and throttle body gaskets; diaphragms used in EGR (exhaust gas recirculation), pressure control (BPT), wastegates, turbo wastegates, actuators, variable turbine geometry (VTG) turbo actuators, exhaust purification valves, etc.; EGR (exhaust gas recirculation) control hoses, emission control hoses, turbocharger turbo oil hoses (supply), turbo oil hoses (return), turbo air hoses, intake hoses, etc. Examples of such hoses include intercooler hoses, turbocharger hoses, hoses connected to the compressor of a turbo engine equipped with an intercooler, exhaust gas hoses, air intake hoses, turbo hoses, DPF (diesel particulate filter) sensor hoses, etc.; air ducts and turbo air ducts; intake manifold gaskets; EGR sealing materials, afterburn prevention valve seats for AB valves, turbine shaft seals (for turbochargers, etc.), and sealing members used in grooved parts such as rocker covers and air intake manifolds used in automobile engines.

Other applications include seals used in exhaust gas control components such as vapor recovery canisters, catalytic converters, exhaust gas sensors, oxygen sensors, etc., seals for vapor recovery and vapor canister solenoid armatures, and intake system manifold gaskets.

It can also be used in diesel engine parts such as O-ring seals for direct injection injectors, rotary pump seals, control diaphragms, fuel hoses, EGR, priming pumps, and boost compensator diaphragms. It can also be used in O-rings, seals, hoses, tubes, diaphragms, gasket materials, and pipes used in urea SCR systems, as well as the urea water tank body and urea water tank seals of urea SCR systems.

Specific uses in the above transmission system include transmission-related bearing seals, oil seals, O-rings, gaskets, torque converter hoses, etc. Other examples include transmission oil seals, automatic transmission oil hoses, automatic transmission fluid (ATF) hoses, O-rings, and gaskets.

Transmissions include AT (automatic transmission), MT (manual transmission), CVT (continuously variable transmission), and DCT (dual clutch transmission).

Other products include oil seals, gaskets, O-rings, and packings for manual or automatic transmissions, oil seals, gaskets, O-rings, and packings for continuously variable transmissions (belt type or toroidal type), as well as packings for ATF linear solenoids, oil hoses for manual transmissions, ATF hoses for automatic transmissions, and CVTF hoses for continuously variable transmissions (belt type or toroidal type).

Specific uses in steering systems include power steering oil hoses and high-pressure power steering hoses.

Examples of forms used in the engine body of an automobile engine include gaskets such as cylinder head gaskets, cylinder head cover gaskets, oil pan packings, and general gaskets, seals such as O-rings, packings, and timing belt cover gaskets, hoses such as control hoses, vibration-damping rubber for engine mounts, control valve diaphragms, and camshaft oil seals.

In the main driving system of an automobile engine, it can be used for shaft seals such as crankshaft seals and camshaft seals.

In the valve train of automobile engines, it can be used for valve stem oil seals for engine valves and valve seats for butterfly valves.

In the lubrication and cooling systems of automobile engines, it can be used for engine oil cooler hoses, oil return hoses, sealing gaskets for engine oil coolers, water hoses around radiators, radiator seals, radiator gaskets, radiator O-rings, vacuum pump oil hoses for vacuum pumps, as well as radiator hoses, radiator tanks, oil pressure diaphragms, fan coupling seals, etc.

Thus, specific examples of uses in the automotive field include engine head gaskets, oil pan gaskets, manifold packings, oxygen sensor seals, oxygen sensor bushings, nitrogen oxide (NO _x ) sensor seals, nitrogen oxide (NO _x ) sensor bushings, sulfur oxide sensor seals, temperature sensor seals, temperature sensor bushings, diesel particle filter sensor seals, diesel particle filter sensor bushings, injector O-rings, injector packings, fuel pump O-rings and diaphragms, gearbox seals, power piston packings, cylinder liner seals, valve stem seals, static valve stem seals, dynamic valve stem seals, automatic transmission front pump seals, rear axle pinion seals, universal joint gaskets, speedometer pinion seals, foot brake piston cups, O-rings and oil seals for torque transmission devices, seals and bearing seals for exhaust gas re-burning devices, re-burning device hoses, Carburetor sensor diaphragms, anti-vibration rubber (engine mounts, exhaust parts, muffler hangers, suspension bushings, center bearings, strut bumper rubber, etc.), suspension anti-vibration rubber (strut mounts, bushings, etc.), drive system anti-vibration rubber (dampers, etc.), fuel hoses, EGR tubes and hoses, twin carburetor tubes, carburetor needle valve core valves, carburetor flange gaskets, oil hoses, oil cooler hoses, ATF hoses, cylinder head gaskets, water pump seals, gearbox seals, needle valve tips, motorcycle reed valve leads, automobile engine oil seals, gasoline hose gun seals, car air conditioner seals, engine intercooler rubber hoses, fuel line connector devices (fuel line connectors) systems), CAC valves, needle tips, engine wiring, filler hoses, car air conditioner O-rings, intake gaskets, fuel tank materials, distributor diaphragms, water hoses, clutch hoses, PS hoses, AT hoses, master back hoses, heater hoses, air conditioning hoses, ventilation hoses, oil filler caps, PS rack seals, rack and pinion boots, CVJ boots, ball joint dust covers, strut dust covers, weather strips, glass runs, center unit packing parts, body sight welts, bumper rubber, door latches, dash insulators, high tension cords, flat belts, poly V-belts, timing belts, toothed belts, V-ribbed belts, tires, wiper blades, diaphragms and plungers for LPG vehicle regulators, diaphragms and valves for CNG vehicle regulators, DME compatible rubber parts, auto tensioner diaphragms and boots, idle speed control diaphragms and valves, auto speed control actuators, vacuum pump diaphragms, check valves and plungers, O.P.S. diaphragms and O-rings, gasoline pressure relief valves, engine cylinder sleeve O-rings and gaskets, wet cylinder sleeve O-rings and gaskets, differential gear seals and gaskets (gear oil seals and gaskets), power steering device seals and gaskets (PSF seals and gaskets), shock absorber seals and gaskets (SAF seals and gaskets), constant velocity joint seals and gaskets, wheel bearing seals and gaskets, metal gasket coating agents, caliper seals, boots, wheel bearing seals, and bladders used in tire vulcanization molding.

In the above-mentioned aircraft, space/rocket, and marine fields, it can be used particularly in fuel systems and lubricating oil systems.

In the aircraft field, the material can be used, for example, as various aircraft sealing parts, various aircraft parts for aircraft engine oil applications, jet engine valve stem seals, gaskets and O-rings, rotating shaft seals, gaskets for hydraulic equipment, firewall seals, fuel supply hoses, gaskets and O-rings, aircraft cables, oil seals and shaft seals, etc.

In the space and rocket fields mentioned above, they can be used, for example, as lip seals, diaphragms, and O-rings for spacecraft, jet engines, missiles, etc., O-rings for gas turbine engine oil, and vibration isolation pads for missile ground control.

In the marine field, it can be used, for example, as aft seals for screw propeller shafts, intake and exhaust valve stem seals for diesel engines, valve seals for butterfly valves, valve seats and shaft seals for butterfly valves, shaft seals for butterfly valves, stern tube seals, fuel hoses, gaskets, O-rings for engines, marine cables, marine oil seals, and marine shaft seals.

In the chemical industry, such as the above-mentioned chemical plants, and in the pharmaceutical industry, such as pharmaceuticals, it can be used in processes that require high chemical resistance, such as processes for manufacturing chemical products such as pharmaceuticals, pesticides, paints, and resins.

Specific uses in the chemical and pharmaceutical fields mentioned above include chemical equipment, chemical pumps and flow meters, chemical piping, heat exchangers, pesticide sprayers, pesticide transfer pumps, gas piping, fuel cells, analytical equipment and physical and chemical equipment (for example, column fittings for analytical equipment and instruments), shrink joints for flue gas desulfurization equipment, nitric acid plants, seals used in power plant turbines, etc., seals used in medical sterilization processes, seals for plating solutions, roller seals for papermaking belts, and joint seals for wind tunnels; O-rings used in chemical equipment such as reactors and agitators, analytical equipment and instruments, chemical pumps, pump housings, valves, tachometers, etc., O-rings for mechanical seals, and O-rings for compressor sealing; packing used in high-temperature vacuum dryers, tube joints for gas chromatography and pH meters, etc., and glass cooling seals for sulfuric acid manufacturing equipment. Examples of suitable applications include: instrument packing; diaphragms used in diaphragm pumps, analytical equipment, and physical and chemical equipment; gaskets used in analytical equipment and meters; ferrules used in analytical equipment and meters; valve seats; U-cups; linings used in chemical equipment, gasoline tanks, wind tunnels, etc., and corrosion-resistant linings for anodized aluminum tanks; coatings for plating masking jigs; valve parts for analytical equipment and physical and chemical equipment; expansion joints in flue gas desulfurization plants; acid-resistant hoses for concentrated sulfuric acid, etc., chlorine gas transfer hoses, oil-resistant hoses, and rainwater drain hoses for benzene and toluene storage tanks; chemical-resistant tubing and medical tubing used in analytical equipment, physical and chemical equipment, etc.; trichlene-resistant rolls and dyeing rolls for textile dyeing; pharmaceutical stoppers; medical rubber stoppers; chemical solution bottles, chemical solution tanks, bags, chemical containers; and protective equipment such as strong acid-resistant and solvent-resistant gloves and boots.

In the photography field, such as the above-mentioned developing machines, the printing field, such as printing machines, and the painting field, such as painting equipment, they can be used as rolls, belts, seals, valve parts, etc. in dry copiers.

Specific uses in the above-mentioned photographic, printing and coating fields include the surface layer of a copier transfer roll, a copier cleaning blade, and a copier belt; rolls (for example, fixing rolls, pressure rolls, etc.) and belts for office automation equipment such as copiers, printers and facsimiles; rolls, roll blades and belts for PPC copiers; rolls for film developing machines and X-ray film developing machines; printing rolls, scrapers, tubes, valve parts and belts for printing machines; ink tubes, rolls and belts for printers; coating rolls, scrapers, tubes and valve parts for coating and painting equipment; developing rolls, gravure rolls, guide rolls, guide rolls for magnetic tape manufacturing coating lines, gravure rolls and coating rolls for magnetic tape manufacturing coating lines, etc.

In the food equipment field, which includes the above-mentioned food plant equipment and household goods, it can be used in food manufacturing processes, food transport devices, or food storage devices.

Specific uses in the food equipment field include seals for plate-type heat exchangers, solenoid valve seals for vending machines, packing for thermos pots, sanitary pipe packing, packing for pressure cookers, water heater seals, heat exchanger gaskets, diaphragms and packing for food processing equipment, and rubber materials for food processing equipment (for example, heat exchanger gaskets, diaphragms, O-rings and other seals, piping, hoses, sanitary packing, valve packing, and filling packing used as a joint between the mouth of a bottle or the like and the filler during filling). Other examples include packing, gaskets, tubes, diaphragms, hoses, and joint sleeves used in products such as alcoholic beverages and soft drinks, filling equipment, food sterilization equipment, brewing equipment, water heaters, and various automatic food vending machines.

In the nuclear power plant equipment field, it can be used for check valves and pressure reducing valves around nuclear reactors, and seals for uranium hexafluoride enrichment equipment.

Specific uses in the above general industrial fields include sealing materials for hydraulic equipment such as machine tools, construction machinery, and hydraulic machinery; seals and bearing seals for hydraulic and lubricating machinery; sealing materials used for mandrels, etc.; seals used for windows in dry cleaning equipment, etc.; cyclotron seals and (vacuum) valve seals, proton accelerator seals, automatic packaging machine seals, pump diaphragms for airborne sulfur dioxide and chlorine gas analyzers (pollution measuring devices), snake pump linings, printing press rolls and belts, conveyor belts, squeeze rolls for pickling steel plates, etc., robot cables, solvent squeeze rolls for aluminum rolling lines, O-rings for couplers, acid-resistant cushioning materials, dust seals and lip rubber for sliding parts of cutting machinery, gaskets for food waste incinerators, friction materials, metal or rubber surface modifiers, and coating materials. It can also be used as gaskets and sealing materials for equipment used in papermaking processes, sealants for clean room filter units, construction sealants, protective coatings for concrete and cement, glass cloth impregnation materials, polyolefin processing aids, polyethylene moldability improving additives, fuel containers for small generators and lawn mowers, pre-coated metals obtained by applying a primer treatment to metal plates, etc. In addition, it can also be used as sheets and belts by impregnating woven fabric and baking it.

Specific uses in the steel industry include steel plate processing rolls in steel plate processing equipment.

Specific uses in the electrical field include insulating oil caps for bullet trains, venting seals for liquid-sealed transformers, transformer seals, oil well cable jackets, seals for ovens such as electric furnaces, window frame seals for microwave ovens, sealants used to bond the wedge and neck of a CRT, sealants for halogen lamps, fixing agents for electrical components, sealants for the terminal treatment of sheathed heaters, and sealants used for insulating and moisture-proofing the lead terminals of electrical equipment. It can also be used as a coating for oil-resistant and heat-resistant electric wires, highly heat-resistant electric wires, chemical-resistant electric wires, highly insulating electric wires, high-voltage power transmission lines, cables, electric wires used in geothermal power generation equipment, and electric wires used around automobile engines. It can also be used as an oil seal or shaft seal for vehicle cables. Furthermore, it can also be used as an electrical insulating material (for example, insulating spacers for various electrical devices, insulating tape for cable joints and ends, and heat-shrinkable tubing), and as a material for electrical and electronic devices used in high-temperature environments (for example, lead wire materials for motors and wire materials for high-temperature furnaces).It can also be used as an encapsulating layer or protective film (back sheet) for solar cells.

In the above-mentioned fuel cell field, it can be used as a sealing material between electrodes and between electrodes and separators in solid polymer fuel cells, phosphate fuel cells, etc., as well as seals, packings, and separators for piping for hydrogen, oxygen, generated water, etc.

In the electronic component field, it can be used as a raw material for heat dissipation materials, electromagnetic wave shielding materials, gaskets for computer hard disk drives (magnetic recording devices), etc. Further, buffer rubber (crash stopper) for hard disk drives, binders for electrode active materials of nickel-metal hydride secondary batteries, binders for active materials of lithium-ion batteries, polymer electrolytes for lithium secondary batteries, binders for the positive electrodes of alkaline storage batteries, binders for EL elements (electroluminescence elements), binders for electrode active materials of capacitors, sealants, sealing agents, quartz coating materials for optical fibers, films and sheets such as optical fiber coating materials, CMOS electronic circuits, transistors, integrated circuits, organic transistors, light-emitting elements, actuators, memory, sensors, coils, capacitors, electronic components such as resistors, potting or coating or adhesive seal for circuit boards, fixing agents for electronic components, sealant modifiers such as epoxy, coating agents for printed circuit boards, modified materials for printed wiring board prepreg resins such as epoxy, shatterproof materials for light bulbs and the like, gaskets for computers, large computer cooling hoses, packing such as gaskets and O-rings for secondary batteries, sealing layers covering one or both sides of the outer surface of an organic EL structure, connectors, and dampers are also used.

In the field of chemical transportation equipment, it can be used for safety valves and shipping valves on trucks, trailers, tank trucks, ships, etc.

In the field of oil, gas, and other energy resource exploration and mining equipment parts, they are used as various sealing materials used when mining oil, natural gas, etc., and as boots for electrical connectors used in oil wells.

Specific uses in the above-mentioned energy resource exploration and mining equipment parts field include drill bit seals, pressure adjustment diaphragms, seals for horizontal drilling motors (stators), stator bearing (shaft) seals, sealing materials used in blowout preventers (BOPs), sealing materials used in rotary blowout preventers (pipe wipers), sealing materials and gas-liquid connectors used in MWDs (real-time drilling information detection systems), logging tool seals (e.g., O-rings, seals, packing, gas-liquid connectors, boots, etc.) used in logging equipment, expansion packers, completion packers and packer seals used therein, seals, packing, and perforators used in cementing equipment. Examples of seals include seals used in drilling equipment, seals, packings and motor linings used in mud pumps, underground audiometer covers, U-cups, composition seating cups, rotary seals, laminated elastomeric bearings, flow control seals, sand control seals, safety valve seals, seals for hydraulic fracturing equipment, seals and packings for linear packers and linear hangers, wellhead seals and packings, seals and packings for chokes and valves, sealing materials for LWD (logging while drilling), diaphragms used in oil exploration and oil drilling applications (for example, diaphragms for supplying lubricating oil to oil drilling pits), gate valves, electronic boots, and sealing elements for drilling guns.

It can also be used for joint seals in kitchens, bathrooms, washrooms, etc.; cover cloths for outdoor tents; seals for printing materials; rubber hoses for gas heat pumps, fluorocarbon-resistant rubber hoses; agricultural films, linings, and weather-resistant covers; and tanks made of laminated steel plates used in the construction and home appliance industries.

It can also be used as an article bonded to metals such as aluminum. Examples of such uses include door seals, gate valves, pendulum valves, solenoid tips, as well as metal-rubber parts bonded to metals such as piston seals, diaphragms, and metal gaskets.

It can also be used for rubber parts, brake shoes, brake pads, etc. on bicycles.

The molded products can also be applied to belts.

Examples of belts include: power transmission belts (including flat belts, V-belts, V-ribbed belts, toothed belts, etc.); conveyor belts (flat belts) used in various high-temperature locations, such as around the engines of agricultural machinery, machine tools, and industrial machinery; conveyor belts for transporting loose and granular materials such as coal, crushed stone, soil, ore, and wood chips in high-temperature environments; conveyor belts used in steel mills with blast furnaces; conveyor belts for applications exposed to high temperatures, such as in precision equipment assembly factories and food factories; V-belts and V-ribbed belts for agricultural machinery, general equipment (e.g., office equipment, printing machines, commercial dryers, etc.), and automobiles; transmission belts for transport robots; toothed belts such as transmission belts for food machinery and machine tools; toothed belts used in automobiles, office equipment, medical equipment, printing machines, etc.

In particular, timing belts are a typical example of toothed belts for automobiles.

The above belt may be of single layer or multi-layer structure.

If the belt has a multi-layer structure, it may consist of a layer obtained by crosslinking a fluororubber crosslinking composition and a layer made of other materials.

In multi-layer belts, layers made of other materials include layers made of other rubbers, layers made of thermoplastic resins, various fiber reinforcement layers, canvas, and metal foil layers.

The molded products can also be used for industrial vibration-damping pads, vibration-damping mats, railway slab mats, pads, automotive vibration-damping rubber, etc. Automotive vibration-damping rubber includes vibration-damping rubber for engine mounts, motor mounts, member mounts, strut mounts, bushings, dampers, muffler hangers, and center bearings.

Other uses include joint components such as flexible joints and expansion joints, boots, grommets, etc. In the marine industry, examples include marine pumps.

Joint components are fittings used in piping and piping equipment, and are used for purposes such as preventing vibrations and noise generated by piping systems, absorbing expansion and contraction and displacement due to temperature and pressure changes, absorbing dimensional fluctuations, and mitigating and preventing the effects of earthquakes and land subsidence.

Flexible joints and expansion joints can be preferably used as complex shaped molded articles for, for example, shipbuilding piping, mechanical piping such as pumps and compressors, chemical plant piping, electrical piping, civil engineering and water supply piping, and automobiles.
The boots can be preferably used as complex shaped molded articles such as automobile boots such as constant velocity joint boots, dust covers, rack and pinion steering boots, pin boots, and piston boots, as well as various industrial boots such as boots for agricultural machinery, boots for industrial vehicles, boots for construction machinery, boots for hydraulic machinery, boots for pneumatic machinery, boots for centralized lubricators, boots for transferring liquids, boots for firefighting, and boots for transferring various liquefied gases.

Molded products can also be used as diaphragms for filter presses, blower diaphragms, water supply diaphragms, liquid storage tank diaphragms, pressure switch diaphragms, accumulator diaphragms, and air spring diaphragms for suspensions, etc.

By adding the molded product to rubber or resin, an anti-slip agent is obtained that produces molded products and coating films that are non-slip in wet environments such as rain, snow, ice, and sweat.

The molded products can also be used as cushioning materials for hot press molding when producing decorative plywood, printed circuit boards, electrical insulating boards, rigid polyvinyl chloride laminates, etc., using melamine resin, phenolic resin, epoxy resin, etc.

The molded articles can also contribute to impermeability of various substrates, such as sealing gaskets for weapons-related applications and protective clothing against contact with aggressive chemical agents.

It can also be used in O-rings, V-rings, X-rings, packings, gaskets, diaphragms, oil seals, bearing seals, lip seals, plunger seals, door seals, lip and face seals, gas delivery plate seals, wafer support seals, barrel seals, and other sealing materials used to seal lubricating oils (engine oil, transmission oil, gear oil, etc.) containing amine-based additives (especially amine-based additives used as antioxidants and detergents/dispersants) used in automobiles, ships, and other transportation applications, as well as in tubes, hoses, various rubber rolls, coatings, belts, valve bodies, etc. It can also be used as a laminating material and lining material.

It can also be used as a coating material for heat-resistant and oil-resistant electrical wires used in lead wires of sensors that come into contact with transmission oil and/or engine oil in internal combustion engines of automobiles, etc. to detect oil temperature and/or oil pressure, and in high-temperature oil environments such as in automatic transmissions and engine oil pans.

In addition, vulcanized coatings may be formed on molded products for use. Specific applications include non-stick, oil-resistant rolls for copiers, weather-resistant and anti-icing weather stripping, rubber stoppers for infusions, rubber vial stoppers, mold release agents, non-stick lightweight conveyor belts, anti-stick coatings for car engine mount gaskets, coatings for synthetic fibers, and bolt components or joints with thin packing coating layers.

In addition, the use of molded products for automobile-related parts also includes use in motorcycle parts with similar structures.

Fuels used in the above-mentioned automobile industry include diesel, gasoline, and diesel engine fuel (including biodiesel fuel).

The molded products can also be used as sealing components for rolling bearings.

Examples of the above-mentioned rolling bearings include ball bearings, roller bearings, bearing units, linear bearings, etc.

Examples of ball bearings include radial ball bearings, thrust ball bearings, and thrust angular ball bearings.

Examples of the above-mentioned radial ball bearings include deep groove ball bearings, angular contact ball bearings, four-point contact ball bearings, self-aligning ball bearings, etc.

The above-mentioned deep groove ball bearings are used, for example, in electric motors, household electrical appliances, office equipment, etc.

The above-mentioned angular contact ball bearings include single-row angular contact ball bearings, duplex angular contact ball bearings, and double-row angular contact ball bearings. Single-row angular contact ball bearings are used in electric motors, household electrical appliances, office equipment, etc., as well as hydraulic pumps and vertical pumps that are subject to axial loads in addition to radial loads. Duplex angular contact ball bearings are used in machine tool main spindles and grinding spindles, etc., where improved shaft rotation accuracy and increased rigidity are required. Double-row angular contact ball bearings are used in electromagnetic clutches for automobile air conditioners, etc.

The above-mentioned four-point contact ball bearings are subjected to axial loads from both directions and are used in reducers and other applications where large bearing widths are not available.

The above-mentioned self-aligning ball bearings are used in places where it is difficult to align the shaft with the housing, or on transmission shafts where the shaft is prone to bending.

The above thrust ball bearings include single-direction thrust ball bearings and double-direction thrust ball bearings, and are applicable to the conventionally known applications in which these ball bearings are used.

The above-mentioned thrust angular ball bearing is used in combination with a double-row cylindrical roller bearing to support the axial load of the main spindle of a machine tool.

Examples of the above-mentioned roller bearings include radial roller bearings, thrust roller bearings, etc.

Examples of the above-mentioned radial roller bearings include cylindrical roller bearings, needle roller bearings, tapered roller bearings, and self-aligning roller bearings.

The above-mentioned cylindrical roller bearings are used in general machinery, machine tools, electric motors, reducers, railway axles, aircraft, etc.

Needle roller bearings are used in general machinery, automobiles, electric motors, etc.

Tapered roller bearings are used in machine tools, automotive and railway axles, rolling mills, reducers, etc.

Self-aligning roller bearings are used in general machinery, rolling mills, papermaking machines, axles, etc.

Examples of the above-mentioned thrust roller bearings include thrust cylindrical roller bearings, thrust needle roller bearings, thrust tapered roller bearings, and thrust self-aligning roller bearings.

Thrust cylindrical roller bearings are used in machine tools, general machinery, etc.

Thrust needle roller bearings are used in automobiles, pumps, general machinery, etc.

Thrust tapered roller bearings are used in general machinery, rolling mills, etc.

Thrust spherical roller bearings are used in cranes, extruders, general machinery, etc.

In addition to being crosslinked and used as molded products, fluororubber crosslinking compositions can also be used as various parts in a variety of industrial fields. Next, we will explain the uses of fluororubber crosslinking compositions.

Fluororubber cross-linking compositions can be used as surface modifiers for metals, rubber, plastics, glass, etc.; sealing and coating materials that require heat resistance, chemical resistance, oil resistance, and non-stickiness, such as metal gaskets and oil seals; non-stick coating materials or bleed barriers for office equipment rolls and office equipment belts; and for impregnating woven fabric sheets and belts or applying them by baking.

Fluororubber cross-linking compositions can be used in the usual way as sealing materials, linings, and sealants for complex shapes by making them highly viscous and highly concentrated; they can be used to form thin films of a few microns by making them low-viscosity; and they can be used to apply pre-coated metal, O-rings, diaphragms, and reed valves by making them medium-viscosity.

It can also be used to coat transport rolls or belts for woven fabrics and paper sheets, printing belts, chemical-resistant tubes, chemical stoppers, fuel hoses, etc.

Examples of substrates that can be coated with the fluororubber cross-linking composition include metals such as iron, stainless steel, copper, aluminum, and brass; glass products such as glass plates and woven and nonwoven glass fiber fabrics; molded and coated products made from general-purpose and heat-resistant resins such as polypropylene, polyoxymethylene, polyimide, polyamideimide, polysulfone, polyethersulfone, and polyetheretherketone; molded and coated products made from general-purpose rubbers such as SBR, butyl rubber, NBR, and EPDM, and heat-resistant rubbers such as silicone rubber and fluororubber; woven and nonwoven fabrics made from natural and synthetic fibers; and the like.

Coatings formed from fluororubber cross-linking compositions can be used in fields requiring heat resistance, solvent resistance, lubricity, and non-stick properties. Specific applications include rolls (e.g., fuser rolls and pressure rolls) and conveyor belts for office automation equipment such as copiers, printers, and facsimiles; sheets and belts; O-rings, diaphragms, chemical-resistant tubes, fuel hoses, valve seals, gaskets for chemical plants, and engine gaskets.

The fluororubber crosslinking composition can also be dissolved in a solvent and used as a paint or adhesive. It can also be used as a paint in the form of an emulsion dispersion (latex).

Fluororubber cross-linking compositions are used as sealing materials and linings for various devices and pipes, etc., and as surface treatment agents for structures made of inorganic and organic substrates such as metals, ceramics, glass, stone, concrete, plastics, rubber, wood, paper, and textiles.

The fluororubber cross-linking composition can be applied to substrates, etc. using dispenser coating or screen printing coating.

The fluororubber crosslinking composition may be used as a coating composition for casting films or for dipping substrates such as fabrics, plastics, metals, or elastomers.

In particular, the fluororubber crosslinking composition, in the form of a latex, may be used to produce coated fabrics, protective gloves, impregnated fibers, O-ring coatings, coatings for fuel system quick connect O-rings, coatings for fuel system seals, coatings for fuel tank rollover valve diaphragms, coatings for fuel tank pressure sensor diaphragms, coatings for oil filters and fuel filter seals, coatings for fuel tank sender seals and sender head fitting seals, coatings for copier fuser rolls, and polymer coating compositions.

They are useful for coating silicone rubber, nitrile rubber, and other elastomers. They are also useful for coating parts made from such elastomers to enhance both the permeation and chemical resistance of the substrate elastomer as well as its thermal stability. Other applications include coatings for heat exchangers, expansion joints, vats, tanks, fans, flue ducts and other ductwork, and containment structures, such as concrete containment structures. Fluoroelastomer crosslinking compositions may also be applied to exposed cross sections of multilayer component structures, such as in hose construction and diaphragm manufacturing processes. Sealing members in connections and joints often consist of hard materials, and fluoroelastomer crosslinking compositions provide improved frictional interfaces, enhanced dimensional interference fits with reduced leakage along the sealing surfaces. The latex enhances seal durability in various automotive system applications.

They can also be used in the manufacture of power steering systems, fuel systems, air conditioning systems, and any joints where hoses and tubes are connected to another component. Another useful application of fluoroelastomer crosslinking compositions is in repairing manufacturing defects (and damage caused by use) in multi-layer rubber structures, such as three-layer fuel hoses. Fluoroelastomer crosslinking compositions are also useful for coating thin steel sheets, which may be formed or embossed before or after paint is applied. For example, multiple layers of coated steel can be assembled to create a gasket between two rigid metal components. A sealing effect is achieved by applying a fluoroelastomer crosslinking composition between the layers. This process can be used to manufacture engine head gaskets and exhaust manifold gaskets, reducing bolt forces and strain on the assembled components while providing better fuel economy and lower emissions due to lower cracking, deflection, and hole distortion.

The fluororubber cross-linking composition can also be used as a coating agent; substrate-integrated gaskets and packings formed by dispenser molding onto substrates containing inorganic materials such as metals and ceramics; and multi-layer products formed by coating substrates containing inorganic materials such as metals and ceramics.

The fluororubber cross-linking composition is also suitable as a wiring material for lightweight, flexible electronic devices and can be used in known electronic components. Examples of electronic components include CMOS electronic circuits, transistors, integrated circuits, organic transistors, light-emitting elements, actuators, memory, sensors, coils, capacitors, and resistors. By using this, flexible electronic devices such as solar cells, various displays, sensors, actuators, electronic artificial skin, sheet-type scanners, Braille displays, and wireless power transmission sheets can be obtained.

Although the above describes an embodiment, it will be understood that various changes in form and details may be made without departing from the spirit and scope of the claims.

Next, we will explain embodiments of the present disclosure using examples, but the present disclosure is not limited to these examples.

The values in the examples were measured using the following methods.

<Monomer composition of fluororubber>
Measurement was carried out using ¹⁹ F-NMR (Bruker AC300P model).

<Fluorine content>
The content was calculated from the composition of the fluororubber measured by ¹⁹ F-NMR.

<Mooney viscosity>
Measurement was carried out in accordance with ASTM D1646-15 and JIS K6300-1:2013 at a measurement temperature of 121°C.

<Glass transition temperature (Tg)>
A DSC curve was obtained by heating 10 mg of a sample at a rate of 20°C/min using a differential scanning calorimeter (DSC822e manufactured by Mettler Toledo or X-DSC7000 manufactured by Hitachi High-Tech Science Corporation). The glass transition temperature was determined as the temperature at the intersection of an extension of the baseline before and after the second-order transition of the DSC curve and a tangent to the inflection point of the DSC curve.

<Heat of fusion>
A differential scanning calorimeter (DSC822e, manufactured by Mettler Toledo, or X-DSC7000, manufactured by Hitachi High-Tech Science) was used to obtain a DSC curve by heating 10 mg of a sample at a rate of 20°C/min, and the heat of fusion was calculated from the magnitude of the melting peak (ΔH) that appeared in the DSC curve.

<Acid value>
The measurement was carried out in accordance with the potentiometric titration method of JIS K0070, except that a 0.01 mol/L ethanol solution of potassium hydroxide was used instead of a 0.1 mol/L ethanol solution of potassium hydroxide.

<Crosslinking characteristics (maximum torque (MH), optimal crosslinking time (T90))>
For the fluororubber crosslinking composition, a crosslinking curve was determined at the temperatures shown in Table 1 during primary crosslinking using a vulcanization tester (MDR H2030 manufactured by M&K Co., Ltd.), and the maximum torque (MH) and optimal crosslinking time (T90) were determined from the change in torque.

<M100, tensile strength and elongation at break>
A 2 mm thick crosslinked sheet was used to prepare a No. 6 dumbbell shaped test piece. Using the obtained test piece and a tensile tester (Tensilon RTG-1310 manufactured by A&D Co., Ltd.), the 100% modulus (M100), tensile strength, and elongation at break at 23°C were measured under the condition of 500 mm/min in accordance with JIS K6251:2010.

<Hardness>
Three 2 mm thick crosslinked sheets were stacked together, and the durometer hardness (type A, peak value, value after 3 seconds) was measured in accordance with JIS K625 3-3 :2012.

<Heat aging test>
A dumbbell No. 6 test piece was prepared using a 2 mm thick crosslinked sheet. The obtained test piece was heat treated at 275°C for 72 hours, and then the tensile strength of the heat-treated test piece was measured using the method described above. The rate of change in tensile strength measured before and after heat treatment was calculated according to the following formula.
ΔX=(X-X ₀ )/X ₀ ×100
ΔX: Rate of change (%)
X ₀ : Measured value before heat treatment
X: Measured value after heat treatment

<Compression set>
Using a small test piece for measuring compression set, measurements were made in accordance with Method A of JIS K6262:2013, at a compression ratio of 25%, a test temperature of 200°C, and a test time of 72 hours.

In the examples and comparative examples, the following materials were used.
Fluorine rubber A:
Vinylidene fluoride/hexafluoropropylene molar ratio: 78/22
Fluorine content: 66%
Mooney viscosity (ML1+10 (121 ° C)): 43
Glass transition temperature: -18°C
Heat of fusion: None observed in the second run Acid value: 0.15 KOH mg/g
Fluorine rubber B:
Vinylidene fluoride/hexafluoropropylene molar ratio: 78/22
Fluorine content: 66%
Mooney viscosity (ML1+10 (121 ° C)): 98
Glass transition temperature: -18°C
Heat of fusion: None observed in the second run Acid value: 0.56 KOH mg/g

MT carbon (N ₂ SA: 8 m ² /g, DBP: 43 ml/100 g)
Calcium hydroxide Magnesium oxide Crosslinking accelerator: a mixture of 91% by mass of benzyldimethyloctadecylammonium chloride and 9% by mass of isopropyl alcohol

Crosslinker-A: 9,9-bis(4-hydroxyphenyl)fluorene Crosslinker-B: Hydroquinone Crosslinker-C: 2-methylresorcinol Crosslinker-D: Bisphenol A
Crosslinker-E: 4,4'-dihydroxydiphenyl ether Crosslinker-F: bis(4-hydroxyphenyl)sulfone Crosslinker-G: 4,4'-dihydroxybenzophenone

Examples 1 and 2 and Comparative Examples 1 to 6
The components were blended according to the formulation in Table 1 and kneaded on an open roll to prepare a fluororubber cross-linking composition. The maximum torque (MH) and optimal cross-linking time (T90) of the obtained fluororubber cross-linking composition are shown in Table 1. Next, the fluororubber cross-linking composition was cross-linked by primary cross-linking (press cross-linking) under the conditions shown in Table 1 and secondary cross-linking (oven cross-linking) at 230°C for 24 hours to obtain a cross-linked sheet (thickness 2 mm) and a small test piece for measuring compression set. The evaluation results of the obtained cross-linked sheet and the results of the compression set test are shown in Table 1.

From the results shown in Table 1, it can be seen that although the same fluororubber was used in Example 1 and Comparative Examples 1 to 6, Example 1, which used a compound represented by general formula (b) as a crosslinking agent, produced molded articles with smaller compression set, greater tensile strength, and a smaller rate of change in tensile strength after heat aging testing than Comparative Examples 1 to 6, which used conventional crosslinking agents. Therefore, it is clear that the use of the fluororubber crosslinking composition disclosed herein enables the production of molded articles with excellent compression set properties at high temperatures, tensile strength, and heat resistance.

Claims (10)

A composition for crosslinking fluororubber, comprising a polyol-crosslinkable fluororubber (a) and a crosslinking agent (b), wherein the crosslinking agent (b) is at least one selected from the group consisting of a compound represented by the following general formula (b) and a salt of said compound with an alkali metal, an alkaline earth metal or an onium compound:
(In the formula, m and n independently represent integers of 1 to 3. ) The fluororubber cross-linking composition according to claim 1, wherein the fluororubber (a) contains vinylidene fluoride units. The fluororubber cross-linking composition according to claim 1 or 2, wherein the content of cross-linking agent (b) is 0.5 to 50 mmol per 100 parts by mass of fluororubber (a). The fluororubber cross-linking composition according to any one of claims 1 to 3, further containing a cross-linking accelerator (c). The fluororubber cross-linking composition according to any one of claims 1 to 4, further containing an acid acceptor (d). The fluororubber cross-linking composition according to any one of claims 1 to 5, further comprising 0.1 to 50 parts by mass of an acid acceptor (d) per 100 parts by mass of the fluororubber (a). The fluororubber cross-linking composition according to any one of claims 1 to 6, further comprising at least one acid acceptor (d) selected from the group consisting of metal oxides, metal hydroxides, alkali metal silicates, metal salts of weak acids, and hydrotalcites. The fluororubber cross-linking composition according to any one of claims 1 to 7, wherein the cross-linking agent (b) is at least one selected from the group consisting of a compound represented by the following formula (b1) and a salt of said compound with an alkali metal, an alkaline earth metal or an onium compound:
A molded article obtained from the fluororubber crosslinking composition described in any one of claims 1 to 8. A sealing material obtained from the fluororubber cross-linking composition described in any one of claims 1 to 8.